The present invention relates to composition and normalization of magnetic resonance (MR) volume data, and more particularly, to automatic composition and normalization of MR volume data.
Magnetic Resonance (MR) is a well known technique for imaging internal structures of a human body. MR scanners are used to scan portions of the human body, resulting in MR volume representing the scanned portions of the body. In some cases, a set of MR volumes covering the whole or part of a body of the patient are obtained using multiple scans. It is then necessary to generate a composite MR image of the patient's body, referred to as a composite MR volume.
Whole-body images in magnetic resonance imaging (MRI) can be generated by combining multiple volumes, also called volume composition. The individual volumes that are being combined have a certain overlap with each other. The overlapping voxels provide the basic information for the composition.
Combining multiple volumes results in generation of the composite MR volume that may include a plurality of the intensity inhomogeneity (IIH) or intensity non-uniformity regions. IIH refers to the slow intensity variation of the same tissue over the volume. This artifact can be due to patient movements, radio-frequency non-uniformity, static-field inhomogeneity, etc. IIH is present in the individual volumes before volume composition is performed. Automated image analysis methods such as those in CAD systems can benefit from an IIH correction step, since IIH could have negative impact on the image analysis algorithm. The presence of IIH can reduce the accuracy of image segmentation and registration, hence decreasing the reliability of subsequent quantitative measurement. IIH has previously been considered in the context of a single volume (before volume composition).